244 MICROBES AND TOXINS 



small doses and so rapidly ? l A vaccinated animal departs from 

 the normal to acquire a new condition ; in sensitized animals 

 under these circumstances there is not the departure from a 

 normal state but there is an appearance of returning towards it. 

 Antianaphylactic vaccination proceeds like a disintoxication 

 and antianaphylatic immunity seems to be a return to the 

 natural immunity. 



The sensitizing injection induces the formation of an antibody ; 

 at the moment of the test injection it is probable that the toxic 

 serum combines with or rather fixes itself on this antibody 

 and this abrupt reaction produces a shock which the nerve-cell 

 resents profoundly. It is " disintoxicated " by it, but with such 

 brutal suddenness as to kill the animal. When by narcosis with 

 anaesthetics or alcohol the sensitiveness of the nerve-cell is 

 diminished, as in the experiment of Besredka and Roux, it 

 becomes disintoxicated during sleep, just as in a surgical 

 operation under chloroform, and wakes up free. If instead of 

 injecting as in the test injection a massive toxic dose, a 

 minute dose is introduced (^\^ c.c. intravenously, for example), 

 the disintoxication of the body, and in particular of the nerve- 

 cells, is carried out gradually, little by little ; in the continuous 

 vaccination method the disintoxication leads back the animal 

 by degrees to its normal condition. 



To the normal condition, but not quite, for the injection 

 leaves as a rule a trace of serum in the body with which it 

 re-sensitizes itself in time ; the guinea-pig has become a fresh 

 animal, and like a fresh animal may be sensitized. It may lose 

 its virginity, regain it, and again lose it. Certain experimenters 

 do not believe that the body ever becomes again normal. 



The digestive tube is, physiologically speaking, as much a 

 barrier to^ the invasion of the body by foreign proteins as it is 



1 " The immunity to a toxin does not appear till after eight days at 

 least and is more pronounced the more numerous and prolonged the 

 successive doses : it is accompanied by the appearance of the antibody in 

 the serum, and finally it never extends to the nerve-centres. On the 

 contrary anaphylactic immunity is established after a single injection, is 

 practically instantaneous, is never accompanied by the appearance of 

 antibodies and finally always extends to the nerve-centres, the brain and 

 spinal cord " (Besredka). 



